The 12 Apostle Cottages, were Lesley Howell, and Trevor Buchannon, were found dead in a car 17 years ago.

The family of murder victim Trevor Buchanan leave court

Trevor Buchannon, who was found dead in a car at Castlerock 17-years ago

The police investigation into the Castlerock murders has been widened, it was revealed last night.

Detectives probing the deaths of RUC officer Trevor Buchanan, (31) and Mrs Lesley Howell (30) who were thought at the time to have died in a suicide pact, are probing other aspects of her dentist husband’s private life.

They are also considering having the bodies exhumed as part of a critical new line of inquiry.

Constable Buchanan and Mrs Howell were found in a car filled with petrol fumes, and even though a Coroner’s Court later ruled they took their own lives after the discovery of a length of piping leading from the exhaust, police will want to establish if they were drugged or disabled in some way before or after the ignition key was switched on.

No decision has been taken, but it’s understood officers in charge of the investigation are looking at possible exhumation.

Forensic and pathology reports as well as witness statements at the time of the inquest hearing have been examined, but detectives will also want to establish what levels, if any, of toxic substances were present.

A source close to the inquiry said last night: “After 18 years, the evidential potential has to be assessed. There are certain things we need to examine, and although nothing is going to happen in the next 48 hours or so, possible exhumation is on the agenda.”

RUC officers involved in the initial investigation in May 1991 after the two bodies were recovered from a car in the seaside town of Castlerock are likely to be interviewed as well. It’s understood at least two have retired.

The ex-partners of the two who died have been charged with the murders. Dr Colin Howell (50), who runs a dental implant surgery in Ballymoney is in custody, but Mrs Hazel Stewart (45), a mother of four from Coleraine, who re-married a senior police officer, Superintendent David Stewart, was granted £15,000 bail, despite Crown objections and police fears she might attempt suicide.

Forensic tests at Dr Howell’s Causeway dental implant studio at Queen Street, Ballymoney have been carried out as part of the widened investigation into his private life.

The property has been closed and boarded since his arrest last Thursday,

Police are looking to interview anybody who spoke to investigating officers at the time of the first investigation or who had any knowledge about the circumstances surrounding the deaths, according to a statement.

An incident room has been set up in Ballycastle.

The statement added: “Inquiries into all the circumstances surrounding these deaths are at an early stage, but all aspects will be examined.”